Arizona Senator John McCain says GOP Primary is the nastiest he has ever seen

J. Scott Applewhite / APSen. John McCain, R-Ariz. talks to reporters on Capitol Hill in Washington on March 5 after making an appeal on the floor of the Senate for the US to lead an "international effort" involving air strikes on Syria's military forces.

From "serial hypocrite" to "corporate raider" to "Rombo," the 2012 Republican Primary has had a lot of name-calling -- possibly the most ever.

Arizona Senator and former Republican presidential nominee John McCain on Sunday told "Meet the Press" host David Gregory that this year's Republican race has been the "nastiest" he's ever seen in terms of negative advertising.

"...the super PACs have played a key role, unfortunately, in my view, because most of them are negative ads," the 75-year-old McCain added. "They've driven up the unfavorables of all of the candidates and made it much more difficult, frankly, to win the election in November."

Negative campaign ads have skyrocketed since 2008. The Washington Post reported that four years ago only six percent of campaign advertising during the GOP Primary was aimed at other Republicans. This year, the number is over 50 percent.

McCain, who endorses Mitt Romney, further criticized the Supreme Court's 2010 Citizens United decision, which prohibited the government from restricting political funding by corporations and unions. The senator predicted that scandal will result from the decision.

"...it's a result of the worst decision the United States Supreme Court has made in many years, the Citizens United decision, where out of naivete and sheer ignorance the majority of the Supreme Court just unloosened all money--released all money now," McCain said. "There will be scandals, David. There will be scandals and then maybe we'll reform again."

The Washington Post and Kantar Media Analysis said that super PACs have spent 72 percent of their money on negative ads while campaigns have spent 27 percent of their money on negative ads.

Ruthann Lariscy, a professor of advertising and public relations at the University of Georgia, wrote on CNN.com that many experts have researched the relationship between negative campaigning and political apathy or disengagement and found that the evidence has mostly been inconclusive.

"...about as many of us seem to be entertained by attack ads as are turned off by them," she writes.

Still Lariscy says that if the attacking advertiser is "too dirty," there is a good possibility the ad will backfire, turning more voters against the attacker than the candidate being attacked.